The collagens are a superfamily of proteins that play a role in maintaining the integrity of various tissues. Collagens are extracellular matrix proteins and have a triple-helical domain as their common structural element. Collagen VI is a major structural component of microfibrils. The basic structural unit of collagen VI is a heterotrimer of the alpha 1(VI), alpha 2(VI), and alpha 3(VI) collagen chains. The alpha 1(VI) and alpha 2(VI) chains are encoded by the COL6A1 and COL6A2 genes, respectively. The protein encoded by the COL6A3 gene is the alpha 3 subunit of type VI collagen (alpha 3(VI) collagen chain) (Bertini et al., 2002 Eur. J. Paediatr. Neurol 6:193-8). COL6A3's gene expression was previously shown to be associated with the progression of breast cancer and was elevated in colon cancer (Smith M J, et al. “Analysis of differential gene expression in colorectal cancer and stroma using fluorescence-activated cell sorting purification” British journal of cancer. 2009; 100:1452-1464; Tilman G et al “Human periostin gene expression in normal tissues, tumors and melanoma: evidences for periostin production by both stromal and melanoma cells” Mol Cancer. 2007; 6:80) and as a prognosis marker of colorectal carcinoma (Qiao J et al. “Stroma derived COL6A3 is a potential prognosis marker of colorectal carcinoma revealed by quantitative proteomics” Oncotarget. 2015 Oct. 6; 6(30): 29929-29946). COL6A3 gene locates 2q37 in the human genome and contains 44 exons. The COL6A3 protein has 3177 amino acids and contains 12 Von Willebrand factor type A (vWA) domains, one fibronectin type 3 domain and one BPTI/Kunitz family of serine protease inhibitors (KU) domain.
T-cell based immunotherapy targets represent peptide epitopes derived from tumor-associated or tumor-specific proteins, which are presented by molecules of the major histocompatibility complex (MHC). These tumor associated antigens (TAAs) can be peptides derived from all protein classes, such as enzymes, receptors, transcription factors, etc. which are expressed and, as compared to unaltered cells of the same origin, usually up-regulated in cells of the respective tumor.
Specific elements of the cellular immune response are capable of specifically recognizing and destroying tumor cells. The isolation of T-cells from tumor-infiltrating cell populations or from peripheral blood suggests that such cells play an important role in natural immune defense against cancer. CD8-positive T-cells in particular, which recognize class I molecules of the major histocompatibility complex (MHC)-bearing peptides of usually 8 to 10 amino acid residues derived from proteins or defective ribosomal products (DRiPs) located in the cytosol, play an important role in this response. The MHC-molecules of the human are also designated as human leukocyte-antigens (HLA).
A TCR is a heterodimeric cell surface protein of the immunoglobulin super-family, which is associated with invariant proteins of the CD3 complex involved in mediating signal transduction. TCRs exist in αβ and γδ forms, which are structurally similar but have quite distinct anatomical locations and probably functions. The extracellular portion of native heterodimeric αβTCR consists of two polypeptides, each of which has a membrane-proximal constant domain, and a membrane-distal variable domain. Each of the constant and variable domains includes an intra-chain disulfide bond. The variable domains contain the highly polymorphic loops analogous to the complementarity determining regions (CDRs) of antibodies. The use of TCR gene therapy overcomes a number of current hurdles. It allows equipping patients' own T cells with desired specificities and generation of sufficient numbers of T cells in a short period of time, avoiding their exhaustion. The TCR will be transduced into central memory T cells or T cells with stem cell characteristics, which may ensure better persistence and function upon transfer. TCR-engineered T cells will be infused into cancer patients rendered lymphopenic by chemotherapy or irradiation, allowing efficient engraftment but inhibiting immune suppression.